@KoiwiGal - The thing I found funny while I was having a look at how they did that ceremony with the golden spike, was that there were actually several golden spikes made, and others made from other kinds of metal like silver.
Different groups wanted to commemorate the day, and even as late as 2005 special commemorative railroad spikes commishioned by wealthy people connected with the railroad were still being found and left to museums.
Oh, and incidentally, the reason the original golden spike is at Stanford is because the guy who came up with the idea for it, was the founder of Standford university.
I believe the special rail tie plate is there as well.
And legend has it that he missed when trying to hammer the spike into the tie plate!